Thermo-electric refrigerator unit



July 13, 1965 G. H. SUDMEIER THERMO-ELECTRIC REFRIGERATOR UNIT 2 Sheets-Sheet 1 Filed March 20, 1963 INVENTOR. G05 72w H; 500445152 BY 2/550 j flrroeusys.

July 13, 1965 su 3,194,023

THERMO-ELECTRIC REFRIGERATOR UNIT Filed March 20, 1963 2 Sheets-Sheet 2 INVENTOR. 0057.01 15!. 500445152 United States Patent 3,194,023 TEERMO-ELECTRIC REFRIGERATOR UNIT Gustav H. Sudmeier, 2708 Torrance Blvd, Torrance, Calif.

Filed Mar. 20, 1963, Ser. No. 266,757 6 Claims. (Cl. 62-3) The present invention relates to refrigeration systems, and particularly to an improved refrigeration unit which employs thermo-electric cells to accomplish cooling with electrical energy.

In past years refrigeration has been accomplished almost universally by systems that circulate fluid which is alternately condensed and evaporated to carry heat from an insulated chamber. The widespread use of such systems attests to their value; however, certain disadvantages are attendant all of the circulating-fluid systems. Specifically, these systems are quite complex and are therefore somewhat expensive even when manufactured in very large quantities. Furthermore, as the systems normally include moving mechanisms, they are subject to wear, and produce noise. Still further, the containment of the fluid refrigerant is sometimes a problem even though it is carried in a completely-sealed system.

The phenomenon of thermo-electric cooling has been recognized for some time as a. possible theory of operation to avoid the disadvantages of circulating-fluid refrigeration systems. In general, this phenomenon occurs when electrical current is passed through certain materials which then develop cold at one junction surface and heat at the other surface. One prior structure utilizing this phenomenon, termed a thermo-electric cell, includes short rods of bismuth telluride stacked in alignment between conductors that carry current to the rod. The conductors are formed into two opposed surfaces at the ends of the rods. In operation, when electrical current is passed through the rods, one of the surfaces becomes cold while the other becomes hot.

Although the efficiency of thermo-electric cell as described above, and in various other structural forms, has been effectively increased during recent years, considerable difliculty has been encounted in incorporating them into a commercially-feasible refrigeration unit. One specific problem is that the hot and cold sides of the cells are physically quite close together. Therefore, considerable difficulty is experienced in heat insulating the two surfaces. Furthermore, in order to obtain the maximum effectiveness of thermo-electric cells in a refrigeration unit, it is important to provide effective heat-transfer paths to accommodate heat flow out of the insulated chamber. Difliculty has been experienced in this regard.

The present invention, in general, comprises a refrigeration unit incorporating at least one thermo-electric cell which is electrically driven to produce cold. A coldproducing surface on each thermo-electric cell is contacted by a cold plate, through a heat-transfer paste or fluid to avod insulating spots on the cold-producing surface. The cold plate extends outwardly to increase its cross section as it enters a cold chamber, thus permitting improved insulation for the cold plate from the heating or hot portion of the thermo-electr-ic cell. The heatproducing surface of each thermo-electric cell is similarly contacted by a heat-radiating plate, which extends outwardly to include integrally-formed fins. A blower then cools the fins by producing an airstream which is directed freshly to the fins adjacent each thermo-electric cell.

An object of the present invention is to provide an improved refrigeration unit.

Another object of the present invention is to provide an economical and efficient refrigeration unit which em- "ice ploys thermo-electric units energized by electrical energy.

Still another object of the present invent-ion is to provide a refrigeration unit employing thermo-electric cells, in which effective insulation and heat transfer provide considerable improvement.

A further object of the invention is to provide a c0mpact refrigeration unit which is relatively silent in operation, requires very little maintenance, and is economical to manufacture and use.

These and other objects and advantages of the present invention will become apparent from a consideration of the following taken in conjunction with the drawings, wherein:

FIGURE 1 is a perspective view of a refrigeration unit constructed in accordance with the present invention;

FIGURE 2 is a vertical sectional view taken along line 22 of FIGURE 1;

FIGURE 3 is a horizontal sectional view taken along line 33 of FIGURE 2; and

FIGURE 4 is a segmented view of a portion of a thermo-electric cell as constructed in the unit of FIGURE 1.

Referring initially to FIGURE 1, the refrigeration unit of the present invention is there incorporated into; a box or unit 12 which provides a cold chamber for the storage of food or other commodities to be refrigerated. The unit 12 is closed by a lid 14 bearing hinges 15 providing access to the refrigerated chamber. The lid may be locked in place by clamps 17, mounted on the sides of the unit as shown. The forward side of the unit (as shown) carries an electrical protective cover 16 containing a receptacle 18 into which a cord from a source of electrical energy may be inserted to energize the refrigeration unit. Above the cover 16 a housing 20 is mounted to contain a blower for drawing air into the unit through the housing 20 and out of the unit through a pair of louvres 22 and 24 as will be considered below in greater detail. In general, the electrical system in the unit of FIGURE 1 is energized by electrical current applied through the receptacle 18 to transfer heat out of the interior of the chamber within the unit 12, the heat being carried by air exiting through the louvres 22 and 24.

Considering the unit in greater detail, reference will now be made to FIGURES 2 and 3, showing sections of the unit as indicated above. The lid 14 of the unit (-FIG- URE 2) is aflixed to the box 26 by hinges 15 so that it may be lifted for access to the refrigerated interior of the box. The lid 14 and the refrigeration box 26 are formed of similar structure comprising double walls 27 and 28 of sheet aluminum, which enclose polyurethane foam linings 30 serving as an effective heat insulator or barrier to heat flow.

The upper edge'surface of the box 26 carries a box collar 32 which may be formed of moulded plastic contacted by a closed loop 34 of polyurethane serving as an insulation gasket for the lid 14 and the box 26 when the lid is lowered to a closed position.

In raising and lowering the lid 14, guidance is provided by a holding arm structure 36 which is affixed between the lid 14 and the box 26 which arm also supports the lid in an open position.

The actual cooling apparatus 36 is aflixed in one of the larger-area walls of the box 26. Cooling is accombattery.

k may be formed of bismuth telluride as well known, and

are electrically connec'ted betweeri conductors as coriduc tors 54 and56. ,The conductors 54 and 56 which may be copper plates, serve to interconnect the ends'of the rods and provide junctions with the rods at which heating and cooling occurs."

Specifically,referring to p is applied first to the forward end of the rod 51A, to pass to the rear of theiro d and into the conductor 54, at which junction cooling occurs. 7 The current then flows through cold plate 66 is afiixedto the inner liner or inner wall- 28 FIGURE 4, electrical current the conductor 54 to the junction of that conductor and'the v j rod 5113, at which cooling again occurs. The current then passes through the rod SlB to the forward conductor 56, -which provides a junction of the heating'type along with a connectionto the, following rod' 51C. Of course,=-the 7 actual cells" 38Qand 40 comprise a'large number of the v individual rods 5 l mounted between many conductors;

however, the illustration of FIGURE 4 indicates the inanner of their interconnection'and mounting. Depending upon themanner in Whichthe lattice of conductors, that is conductors 54 and 56, are arranged, variouscombina- V tions of paralleland serial interconnections may be af- 1 fected. -However, in therpresentfsystem'a satisfactory mode of operation has-been accomplished by arranging ,the conductors and the'rods to provide l2-volt operation useful in conjunction with a conventional automobile Referring now to FIGURES 2 and 3, it may be seen that the rods 51 are held between the plate conductors 56 to formlthe relatively flat, rectangular thermo-electric cells 38 and 40. The surfaces of the cells 38 and 40 are contacted by a heat-transfer liquid or paste coating 57 I 64'engages the heat-developing surfaces 48and 50 of the V cellsthrough the 'coatings 57. The plates 60 and 62 may be formed of aluminum which is, anodized. The

anodizedsurfaces of the'plates 60 and 62f(engaging the cells 38' and '40) are coated with a very thin layer of electrical insulating material-"as 'For'mvar enamel. Of.

course, if desired, the entireplates may be coated. Therestrays 73 (FIGURE 2): in} separate chambers which of the box by metal screws 72 (FIGURE 3), which pass through arear wall ofianice-tray box 74 which may be formed as a single integralaluminurn casting. These mating surfaces are alsofcoatedwith heat conductive paste .or liquid as silicone grease to avoid insulating air pockets. The surface of the box'74 which engages the wall 28 mates with the area of the cold plate 60 aflixed to the wall. Thereforenan eflective cooling path is developed by the structure. Thebox 74 maycontain a pair of ice are closed bysp'r-ing-biased' hinged" doors 76. Consider now the s't ructur'e'c for transferring the heat away'frorn the cells 38'and and out of thecooling 'apparatus36. Referring to" FIGURE 2, the exterior of the finsed extend outward toabutt the outer wall 28 of the box 26 actingas a shroud to'close' off the inner Wall Of the boxp Furthermore; this abutrnent,providesiphysical supportfor thecooling apparatus 36.

The fins64 also provide'transverse channels extending across the ward the box. These channels are closed by between.

79 (FIGURE 2) and discharge'louvres Ziland 22. P0- sitioned within-the. housing 20 is a blower 80(FIGURE 2), driven by; an electric motor 82 energizedthrough conductors 8,4 which are connected'to the electrical control box 86 within the cover 16. "The, control box 86 isalso regulates the application of power to the motor 82 and the cells'38 and 40 in accordance with the temperature of the'cold plate 60, as well known in the prior art.

In the'manufacture of the unit of the presentinvention, the cells 38 511M140 are first assembled injaccordance with 3 various wellknown prior techniques. Next, the exterior surfaces of these cells are coatedwithheat-conductive paste or fluid to form the coating 57, and plastic screws 66 are'inserted to join plates 62 and'60 clamping the cells Next, the ice-tray 130x 74 ispositioned' inside the refrigeration chamber and screws 72 are inserted through the-rear wall of the box into the cold plate 60,

thereby mounting the box 74 and the'cooling apparatus fore, the hot and cold surfaces of the cells 38 and 40 are:

electrically insulated from the plates 60 and 6 2; however, a good heat-transfer path exists between these elements.

I The cold. plate 60 is afiixed to the hot plate'62 by plas-' tic screws 66 (FIGURE 3) which pass through short bosses 68 formed in thefacing surfaces of the two'plates.

insulating 'as "well as heat zinsulating, so that'neither a heat path or a current path existsbetween the two plates I as a result of the coupling screws 66. I

The facing surfaces of the'plates '60 and 62 taper'awa from one .another at the edges of the cells 38 and 49 in all four directions; This tapering gradually and smoothly increases the cross-sectional area-of the plates. There fore, a structure'is provided with no sharp abutr'nents, yet which permits greater insulation of. the hot'plate from the cold plate. That is, the tapered'surfaces'permit an To provide support for the cooling apparatiis66, the

-36. Thereaftenthe electrical connections to the thermo bulb skand-thecells 38 and '40 are brought to the control box 86- As a l'aststage of assembly, the motor82 (mounted in the housing 20) is'aflixed to the exterior In using the'unit of the present invention as described in exemplary form above, an electrical'cord is connected 1 motor SZand the cells 38' and 40. Upon initial energization, the/thermo bulb 86 senses a relatively high temperature at the cold plate ;ftherefore, acontrol switch in the control box 86' permits the energization of the motor These bosses facilitate drilling the threaded bores which receive the screws 66. It is to be noted,'that1the plastic material of the screws 66 renders these screwselectrically 82and .the eells 38 and 40. Upon energization of the cells38 and 40, heat is generated at their external surfaces '48'andj 50. while cold develops at the internal'surfaces 44 and 46. As a result of the effective heat-transfer paths set up with respect to these surfaces, heat is rapidly moved from the box 74 and the interior wall 28 through the cold plate 60, and the cells 38 and 40, into the fins 64.

The blower their forces air at ambient temperature through the exhaust duct 78 to form a jet which draws air freshly over the fins-adjacent each'of the separate cells '38 and tii. Asa result, ambient'air' strikes the fins adjacent each cell ,at substantially ambient temperature, Therefore; the

.heat-transfer between the fins 64 and the. air is more effective, permitting the air to be raised in temperature and-carry heat from the fins 64.

The feature of applying freshco'o 'ling. air to the heat 1 radiators for each cell individually constitutes an important feature of the -presentjinvention, permitting more effective operation of the unit. Therefore, heat is removed from the ice-tray box 74 until the refrigerated chamber is cooled to the temperature established by the control unit, at which time the motor 82 and the cells 38 and 40 are de-energized until a subsequent temperature rise. In view of the structure for insulating the cold cell surfaces 44 and 46 from the warm cell surfaces 43 and 50', along with the effective heat-transfer paths, the operation cycle is of relatively short time.

In this regard, an important feature of the present invention resides in the use of heat-insulating means as the screws 66 to join tapered surface transfer plates with the thermoelectric cells therebetween.

Still another important feature of the present invention resides in the use of heat-transfer paste or liquid to couple various members in the heat-transfer path whereby to avoid insulating spots on surfaces contained in the heattransfer path.

Still a further important feature resides in the structure of anodized aluminum heat-transfer plates adjacent the thermo-electric cells, which plates are rendered electrically-insulating relative the cells by coating their anodized surfaces with a layer which is not heat-insulating.

These and other features of the present invention are evident from the embodiment described herein; however, the scope of the invention is not to be limited to this embodiment, but rather is to be defined by the following claims.

What is claimed is:

1. A refrigeration unit, comprising: a plurality of thermo-electric cells for receiving electrical energy to produce a temperature differential between a first surface and a second surface whereby said first surface cools and said second surface warms; a first heat-conductive member having plural first faces to engage said second surfaces, said first faces being separated by channels tapering to a bottom therein, said member further including radiating fins remote from said faces; a deformable layer of heat-transfer paste-like material between said first faces and said second surfaces; a second heat-conductive member including a first plate with plural second faces to engage said first surfaces, said second faces being separated by channels tapering to a bottom therein, and a second plate adapted to be affixed to said first plate; a deformable layer of heat-transfer paste-like material between said second faces and said first surfaces; an enclosure means to provide an insulated volume; means for mounting said plurality of thermo-electric cells in said enclosure, including an inner wall of said enclosure held between said first plate and said second plate; and a blower means for directing an airstream into said fins whereby said airstream is divided to flow over said fins.

2. A refrigeration unit, comprising: a plurality of thermo-electric cells for receiving electrical energy to produce a temperature differential between a first surface and a second surface whereby said first surface cools and said second surface warms; a first heat-conductive member having plural first faces to engage said second surfaces, said first faces being separated by channels tapering to a bottom therein, said member further including radiating fins remote from said faces; a deformable layer of heattransfer paste-like material between said first faces and said second surfaces; a second heat-conductive member including a first plate with plural second faces to engage said first surfaces, said second faces being separated by channels tapering to a bottom therein, and a second plate adapted to be afiixed to said first plate; a deformable layer of heat-transfer paste-like material between said second faces and said first surfaces; an enclosure means to provide an insulated volume; means for mounting said plurality of thermo-electric cells in said enclosure, including an inner wall of said enclosure held between said first plate and said second plate.

3. A refrigeration unit, comprising: a plurality of thermo-electric cells for receiving electrical energy to produce a temperature differential between a first surface and a second surface whereby said first surface cools and said second surface warms; a first heat-conductive member having plural first faces to engage said second surfaces, said first faces being separated by channels taperring to a bottom therein, said member further including radiating fins remote from said faces; a deformable layer of heattransfer paste-like material beween said first faces and said second surfaces; a second heat conductive member including a first plate with plural second faces to engage said first surfaces, said second faces being separated by channels tapering to a bottom therein, and a second plate adapted to be affiXed to said first plate; a deformable layer of heat-transfer paste-like material between said second faces and said first surfaces; an enclosure means to provide an insulated volume; means for mounting said plurality of thermo-electric cells in said enclosure, and a blower means for directing an airstream into said fins whereby said airstream is divded to flow over said fins, said blower being positioned at an exhaust location for said airstream directed over said fins.

4. The invention according to claim 2 in which said heat-transfer paste-like material is a relatively viscous silicone grease.

5. The invention according to claim 2 in which said thermo-electric cells comprise rods extending between said first and second surfaces and have a substantially metallic composition including bismuth telluride.

6. The invention according to claim 3 which further includes at least one polyurethane foam body disposed in at least one of said channels.

References Cited by the Examiner UNITED STATES PATENTS 2,334,284 11/43 Philipp 62 517 2,625,378 1/53 Nason -171 2,844,638 7/58 Lindenblad 623 2,932,953 4/60 Becket 623 2,978,875 4/61 Lackey 62-3 3,018,631 1/62 Bury 62-3 3,100,969 8/63 Elfving 62-3 ROBERT A. OLEARY, Primary Examiner. WILLIAM J. WYE, Examiner. 

1. A REFRIGERATION UNIT, COMPRISING: A PLURALITY OF THERMO-ELECTRIC CELLS FOR RECEIVING ELECTRICAL ENERGY TO PRODUCE A TEMPERATURE DIFFERENTIAL BETWEEN A FIRST SURFACE AND A SECOND SURFACE WHEREBY SAID FIRST SURFACE COOLS AND SAID SECOND SURFACE WARMS; A FIRST HEAT-CONDUCTIVE MEMBER HAVING PLURAL FIRST FACES TO ENGAGE SAID SECOND SURFACES, SAID FIRST FACES BEING SEPARATED BY CHANNELS TAPERING TO A BOTTOM THEREIN, SAID MEMBER FURTHER INCLUDING RADIATING FINS REMOTE FROM SAID FACES; A DEFORMABLE LAYER OF HEAT-TRANSFER PASTE-LIKE MATERIAL BETWEEN SAID FIRST FACES AND SAID SECOND SURFACES; A SECOND HEAT-CONDUCTIVE MEMBER INCLUDING A FIRST PLATE WITH PLURAL SECOND FACES TO ENGAGE SAID FIRST SURFACES, SAID SECOND FACES BEING SEPARATED BY CHANNELS TAPERING TO A BOTTOM THEREIN, AND A SECOND PLATE ADAPTED TO BE AFFIXED TO SAID FIRST PLATE; A DEFORMABLE LAYER OF HEAT-TRANSFER PASTE-LIKE MATERIAL BETWEEN SAID SECOND FACES AND SAID FIRST SURFACES; AN ENCLOSURE MEANS TO PROVIDE AN INSULATED VOLUME; MEANS FOR MOUNTING SAID PLURALITY OF THERMO-ELECTRIC CELLS IN SAID ENCLOSURE, INCLUDING AN INNER WALL OF SAID ENCLOSURE HELD BETWEEN SAID FIRST PLATE AND SAID SECOND PLATE; AND A BLOWER MEANS FOR DIRECTING AN AIRSTREAM INTO SAID FINS WHEREBY SAID AIRSTREAM IS DIVIDED TO FLOW OVER SAID FINS. 